package 多线程.Test;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

/**
 * ReadWriteLock
 */
public class ReadWriteLockDemo {
    /**
     * 说白了，写的时候不能读，读的时候不能写。但是可以多个线程一起读，不可以多个线程一起写。
     */
    public static void main(String[] args) {
        MyCacheLock myCacheLock = new MyCacheLock();
        //写入操作
        for(int i=0;i<5;i++){
            final int temp = i;
            new Thread(()->{
                myCacheLock.put(temp+"",temp+"");
            },String.valueOf(i)).start();
        }
        //读取操作
        for(int i=0;i<5;i++){
            final int temp = i;
            new Thread(()->{
                myCacheLock.get(temp+"");
            },String.valueOf(i)).start();
        }
    }
}
//自定义一个缓存
class MyCache{
    private volatile Map<String,Object> map = new HashMap<>();
    //存,写
    public void put(String key,Object value){
        System.out.println(Thread.currentThread().getName()+"写入"+key);
        map.put(key,value);
        System.out.println(Thread.currentThread().getName()+"写入ok");
    }
    //取,读
    public void get(String key){
        System.out.println(Thread.currentThread().getName()+"读取"+key);
        Object o = map.get(key);
        System.out.println(Thread.currentThread().getName()+"读取ok");
    }
}
class MyCacheLock{
    private volatile Map<String,Object> map = new HashMap<>();
    //读写锁,更加细粒度的控制
    private ReadWriteLock readWriteLock = new ReentrantReadWriteLock();
    //存,写   写入的时候只希望同时只有一个线程写
    public void put(String key,Object value){
        readWriteLock.writeLock().lock();
        try{
            System.out.println(Thread.currentThread().getName()+"写入"+key);
            map.put(key,value);
            System.out.println(Thread.currentThread().getName()+"写入ok");
        }catch (Exception e){
            e.printStackTrace();
        }finally{
            readWriteLock.writeLock().unlock();
        }
    }
    //取,读    所有人都可以去读我写入的内容
    public void get(String key){
        readWriteLock.readLock().lock();
        try{
            System.out.println(Thread.currentThread().getName()+"读取"+key);
            Object o = map.get(key);
            System.out.println(Thread.currentThread().getName()+"读取ok");
        }catch(Exception e){
            e.printStackTrace();
        }finally{
            readWriteLock.readLock().unlock();
        }
    }
}